On-demand scheduling request design

ABSTRACT

An on-demand scheduling request (SR) design is disclosed. Such an on-demand or triggered SR operation provides pre-configuration of user equipments (UEs) with triggered SR resources. Base stations may also configure UEs to monitor for a trigger signal within a bit field of control signaling from the base station. Upon detecting the trigger signal within such bit field, the UEs may use the triggered SR resources for transmitting triggered SR requests. Such use of the triggered SR resources may be in response to UEs detected cancelation of other periodic configured SR resources.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 63/047,767, entitled, “ON-DEMAND SCHEDULING REQUEST DESIGN,” filed on Jul. 2, 2020, which is expressly incorporated by reference herein in its entirety.

BACKGROUND Field

Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to an on-demand scheduling request (SR) design.

Background

Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and the like. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the Universal Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3GPP). Examples of multiple-access network formats include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks.

A wireless communication network may include a number of base stations or node Bs that can support communication for a number of user equipments (UEs). A UE may communicate with a base station via downlink and uplink. The downlink (or forward link) refers to the communication link from the base station to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the base station.

A base station may transmit data and control information on the downlink to a UE and/or may receive data and control information on the uplink from the UE. On the downlink, a transmission from the base station may encounter interference due to transmissions from neighbor base stations or from other wireless radio frequency (RF) transmitters. On the uplink, a transmission from the UE may encounter interference from uplink transmissions of other UEs communicating with the neighbor base stations or from other wireless RF transmitters. This interference may degrade performance on both the downlink and uplink.

As the demand for mobile broadband access continues to increase, the possibilities of interference and congested networks grows with more UEs accessing the long-range wireless communication networks and more short-range wireless systems being deployed in communities. Research and development continue to advance wireless technologies not only to meet the growing demand for mobile broadband access, but to advance and enhance the user experience with mobile communications.

SUMMARY

In one aspect of the disclosure, a method of wireless communication includes receiving, by a user equipment (UE), a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered scheduling request (SR) transmission, monitoring, by the UE, for a trigger signal triggering transmission of a triggered SR, and transmitting, by the UE, the triggered SR using the transmission resource in response to detecting the trigger signal.

In an additional aspect of the disclosure, an apparatus configured for wireless communication includes means for receiving, by a UE, a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered SR transmission, means for monitoring, by the UE, for a trigger signal triggering transmission of a triggered SR, and means for transmitting, by the UE, the triggered SR using the transmission resource in response to detecting the trigger signal.

In an additional aspect of the disclosure, a non-transitory computer-readable medium having program code recorded thereon. The program code further includes code to receive, by a UE, a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered SR transmission, code to monitor, by the UE, for a trigger signal triggering transmission of a triggered SR, and code to transmit, by the UE, the triggered SR using the transmission resource in response to detecting the trigger signal.

In an additional aspect of the disclosure, an apparatus configured for wireless communication is disclosed. The apparatus includes at least one processor, and a memory coupled to the processor. The processor is configured to receive, by a UE, a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered SR transmission, to monitor, by the UE, for a trigger signal triggering transmission of a triggered SR, and to transmit, by the UE, the triggered SR using the transmission resource in response to detecting the trigger signal.

The foregoing has outlined rather broadly the features and technical advantages of examples according to the disclosure in order that the detailed description that follows may be better understood. Additional features and advantages will be described hereinafter. The conception and specific examples disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure. Such equivalent constructions do not depart from the scope of the appended claims. Characteristics of the concepts disclosed herein, both their organization and method of operation, together with associated advantages will be better understood from the following description when considered in connection with the accompanying figures. Each of the figures is provided for the purpose of illustration and description, and not as a definition of the limits of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the present disclosure may be realized by reference to the following drawings. In the appended figures, similar components or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If just the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.

FIG. 1 is a block diagram illustrating details of a wireless communication system.

FIG. 2 is a block diagram illustrating a design of a base station and a UE configured according to one aspect of the present disclosure.

FIG. 3 is a block diagram illustrating example blocks executed by a UE to implement one aspect of the present disclosure.

FIG. 4 is a block diagram illustrating an NR-U network having UEs in communication with base station and configured for on-demand or triggered SR according to aspects of the present disclosure.

FIG. 5 is a block diagram illustrating an NR-U network having UEs in communication with base station and configured for on-demand or triggered SR according to aspects of the present disclosure.

FIG. 6 is a block diagram illustrating an example configuration of a UE configured according to one aspect of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to limit the scope of the disclosure. Rather, the detailed description includes specific details for the purpose of providing a thorough understanding of the inventive subject matter. It will be apparent to those skilled in the art that these specific details are not required in every case and that, in some instances, well-known structures and components are shown in block diagram form for clarity of presentation.

This disclosure relates generally to providing or participating in authorized shared access between two or more wireless communications systems, also referred to as wireless communications networks. In various embodiments, the techniques and apparatus may be used for wireless communication networks such as code division multiple access (CDMA) networks, time division multiple access (TDMA) networks, frequency division multiple access (FDMA) networks, orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA) networks, LTE networks, GSM networks, 5^(th) Generation (5G) or new radio (NR) networks, as well as other communications networks. As described herein, the terms “networks” and “systems” may be used interchangeably.

An OFDMA network may implement a radio technology such as evolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and the like. UTRA, E-UTRA, and Global System for Mobile Communications (GSM) are part of universal mobile telecommunication system (UMTS). In particular, long term evolution (LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS and LTE are described in documents provided from an organization named “3rd Generation Partnership Project” (3GPP), and cdma2000 is described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2). These various radio technologies and standards are known or are being developed. For example, the 3rd Generation Partnership Project (3GPP) is a collaboration between groups of telecommunications associations that aims to define a globally applicable third generation (3G) mobile phone specification. 3GPP long term evolution (LTE) is a 3GPP project which was aimed at improving the universal mobile telecommunications system (UMTS) mobile phone standard. The 3GPP may define specifications for the next generation of mobile networks, mobile systems, and mobile devices. The present disclosure is concerned with the evolution of wireless technologies from LTE, 4G, 5G, NR, and beyond with shared access to wireless spectrum between networks using a collection of new and different radio access technologies or radio air interfaces.

In particular, 5G networks contemplate diverse deployments, diverse spectrum, and diverse services and devices that may be implemented using an OFDM-based unified, air interface. In order to achieve these goals, further enhancements to LTE and LTE-A are considered in addition to development of the new radio technology for 5G NR networks. The 5G NR will be capable of scaling to provide coverage (1) to a massive Internet of things (IoTs) with an ultra-high density (e.g., ˜1M nodes/km²), ultra-low complexity (e.g., ˜10 s of bits/sec), ultra-low energy (e.g., ˜10+ years of battery life), and deep coverage with the capability to reach challenging locations; (2) including mission-critical control with strong security to safeguard sensitive personal, financial, or classified information, ultra-high reliability (e.g., ˜99.9999% reliability), ultra-low latency (e.g., 1 ms), and users with wide ranges of mobility or lack thereof; and (3) with enhanced mobile broadband including extreme high capacity (e.g., ˜10 Tbps/km²), extreme data rates (e.g., multi-Gbps rate, 100+ Mbps user experienced rates), and deep awareness with advanced discovery and optimizations.

The 5GNR may be implemented to use optimized OFDM-based waveforms with scalable numerology and transmission time interval (TTI); having a common, flexible framework to efficiently multiplex services and features with a dynamic, low-latency time division duplex (TDD)/frequency division duplex (FDD) design; and with advanced wireless technologies, such as massive multiple input, multiple output (MIMO), robust millimeter wave (mmWave) transmissions, advanced channel coding, and device-centric mobility. Scalability of the numerology in 5G NR, with scaling of subcarrier spacing, may efficiently address operating diverse services across diverse spectrum and diverse deployments. For example, in various outdoor and macro coverage deployments of less than 3 GHz FDD/TDD implementations, subcarrier spacing may occur with 15 kHz, for example over 1, 5, 10, 20 MHz, and the like bandwidth. For other various outdoor and small cell coverage deployments of TDD greater than 3 GHz, subcarrier spacing may occur with 30 kHz over 80/100 MHz bandwidth. For other various indoor wideband implementations, using a TDD over the unlicensed portion of the 5 GHz band, the subcarrier spacing may occur with 60 kHz over a 160 MHz bandwidth. Finally, for various deployments transmitting with mmWave components at a TDD of 28 GHz, subcarrier spacing may occur with 120 kHz over a 500 MHz bandwidth.

The scalable numerology of the 5G NR facilitates scalable TTI for diverse latency and quality of service (QoS) requirements. For example, shorter TTI may be used for low latency and high reliability, while longer TTI may be used for higher spectral efficiency. The efficient multiplexing of long and short TTIs to allow transmissions to start on symbol boundaries. 5G NR also contemplates a self-contained integrated subframe design with uplink/downlink scheduling information, data, and acknowledgement in the same subframe. The self-contained integrated subframe supports communications in unlicensed or contention-based shared spectrum, adaptive uplink/downlink that may be flexibly configured on a per-cell basis to dynamically switch between uplink and downlink to meet the current traffic needs.

Various other aspects and features of the disclosure are further described below. It should be apparent that the teachings herein may be embodied in a wide variety of forms and that any specific structure, function, or both being disclosed herein is merely representative and not limiting. Based on the teachings herein one of an ordinary level of skill in the art should appreciate that an aspect disclosed herein may be implemented independently of any other aspects and that two or more of these aspects may be combined in various ways. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, such an apparatus may be implemented or such a method may be practiced using other structure, functionality, or structure and functionality in addition to or other than one or more of the aspects set forth herein. For example, a method may be implemented as part of a system, device, apparatus, and/or as instructions stored on a computer readable medium for execution on a processor or computer. Furthermore, an aspect may comprise at least one element of a claim.

FIG. 1 is a block diagram illustrating an example of a wireless communications system 100 that supports an on-demand or triggered scheduling request (SR) in accordance with aspects of the present disclosure. Such an on-demand or triggered SR operation provides pre-configuration of UEs 115 with triggered SR resources. Base stations 105 may also configure UEs 115 to monitor for an trigger signal within a bit field of control signaling from base stations 105. Upon detecting the trigger signal within such bit field, UEs 115 may use the triggered SR resources for transmitting triggered SR requests. Such use of the triggered SR resources may be in response to UEs 115 detected cancelation of other periodic configured SR resources. The wireless communications system 100 includes base stations 105, UEs 115, and a core network 130. In some examples, the wireless communications system 100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A) network, an LTE-A Pro network, or NR network. In some cases, wireless communications system 100 may support enhanced broadband communications, ultra-reliable (e.g., mission critical) communications, low latency communications, or communications with low-cost and low-complexity devices.

Base stations 105 may wirelessly communicate with UEs 115 via one or more base station antennas. Base stations 105 described herein may include or may be referred to by those skilled in the art as a base transceiver station, a radio base station, an access point, a radio transceiver, a NodeB, an eNodeB (eNB), a next-generation NodeB or giga-NodeB (either of which may be referred to as a gNB), a Home NodeB, a Home eNodeB, or some other suitable terminology. Wireless communications system 100 may include base stations 105 of different types (e.g., macro or small cell base stations). The UEs 115 described herein may be able to communicate with various types of base stations 105 and network equipment including macro eNBs, small cell eNBs, gNBs, relay base stations, and the like.

Each base station 105 may be associated with a particular geographic coverage area 110 in which communications with various UEs 115 is supported. Each base station 105 may provide communication coverage for a respective geographic coverage area 110 via communication links 125, and communication links 125 between a base station 105 and a UE 115 may utilize one or more carriers. Communication links 125 shown in wireless communications system 100 may include uplink transmissions from a UE 115 to a base station 105, or downlink transmissions from a base station 105 to a UE 115. Downlink transmissions may also be referred to as forward link transmissions while uplink transmissions may also be referred to as reverse link transmissions.

The geographic coverage area 110 for a base station 105 may be divided into sectors making up a portion of the geographic coverage area 110, and each sector may be associated with a cell. For example, each base station 105 may provide communication coverage for a macro cell, a small cell, a hot spot, or other types of cells, or various combinations thereof. In some examples, a base station 105 may be movable and, therefore, provide communication coverage for a moving geographic coverage area 110. In some examples, different geographic coverage areas 110 associated with different technologies may overlap, and overlapping geographic coverage areas 110 associated with different technologies may be supported by the same base station 105 or by different base stations 105. The wireless communications system 100 may include, for example, a heterogeneous LTE/LTE-A/LTE-A Pro or NR network in which different types of base stations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used for communication with a base station 105 (e.g., over a carrier), and may be associated with an identifier for distinguishing neighboring cells (e.g., a physical cell identifier (PCID), a virtual cell identifier (VCID)) operating via the same or a different carrier. In some examples, a carrier may support multiple cells, and different cells may be configured according to different protocol types (e.g., machine-type communication (MTC), narrowband Internet-of-things (NB-IoT), enhanced mobile broadband (eMBB), or others) that may provide access for different types of devices. In some cases, the term “cell” may refer to a portion of a geographic coverage area 110 (e.g., a sector) over which the logical entity operates.

UEs 115 may be dispersed throughout the wireless communications system 100, and each UE 115 may be stationary or mobile. A UE 115 may also be referred to as a mobile device, a wireless device, a remote device, a handheld device, or a subscriber device, or some other suitable terminology, where the “device” may also be referred to as a unit, a station, a terminal, or a client. A UE 115 may also be a personal electronic device such as a cellular phone (UE 115 a), a personal digital assistant (PDA), a wearable device (UE 115 d), a tablet computer, a laptop computer (UE 115 g), or a personal computer. In some examples, a UE 115 may also refer to a wireless local loop (WLL) station, an Internet-of-things (IoT) device, an Internet-of-everything (IoE) device, an MTC device, or the like, which may be implemented in various articles such as appliances, vehicles (UE 115 e and UE 115 f), meters (UE 115 b and UE 115 c), or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or low complexity devices, and may provide for automated communication between machines (e.g., via machine-to-machine (M2M) communication). M2M communication or MTC may refer to data communication technologies that allow devices to communicate with one another or a base station 105 without human intervention. In some examples, M2M communication or MTC may include communications from devices that integrate sensors or meters to measure or capture information and relay that information to a central server or application program that can make use of the information or present the information to humans interacting with the program or application. Some UEs 115 may be designed to collect information or enable automated behavior of machines. Examples of applications for MTC devices include smart metering, inventory monitoring, water level monitoring, equipment monitoring, healthcare monitoring, wildlife monitoring, weather and geological event monitoring, fleet management and tracking, remote security sensing, physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reduce power consumption, such as half-duplex communications (e.g., a mode that supports one-way communication via transmission or reception, but not transmission and reception simultaneously). In some examples, half-duplex communications may be performed at a reduced peak rate. Other power conservation techniques for UEs 115 include entering a power saving “deep sleep” mode when not engaging in active communications, or operating over a limited bandwidth (e.g., according to narrowband communications). In other cases, UEs 115 may be designed to support critical functions (e.g., mission critical functions), and a wireless communications system 100 may be configured to provide ultra-reliable communications for these functions.

In certain cases, a UE 115 may also be able to communicate directly with other UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device (D2D) protocol). One or more of a group of UEs 115 utilizing D2D communications may be within the geographic coverage area 110 of a base station 105. Other UEs 115 in such a group may be outside the geographic coverage area 110 of a base station 105, or be otherwise unable to receive transmissions from a base station 105. In some cases, groups of UEs 115 communicating via D2D communications may utilize a one-to-many (1:M) system in which each UE 115 transmits to every other UE 115 in the group. In some cases, a base station 105 may facilitate the scheduling of resources for D2D communications. In other cases, D2D communications may be carried out between UEs 115 without the involvement of a base station 105.

Base stations 105 may communicate with the core network 130 and with one another. For example, base stations 105 may interface with the core network 130 through backhaul links 132 (e.g., via an S1, N2, N3, or other interface). Base stations 105 may communicate with one another over backhaul links 134 (e.g., via an X2, Xn, or other interface) either directly (e.g., directly between base stations 105) or indirectly (e.g., via core network 130).

The core network 130 may provide user authentication, access authorization, tracking, Internet Protocol (IP) connectivity, and other access, routing, or mobility functions. The core network 130 may be an evolved packet core (EPC), which may include at least one mobility management entity (MME), at least one serving gateway (S-GW), and at least one packet data network (PDN) gateway (P-GW). The MME may manage non-access stratum (e.g., control plane) functions such as mobility, authentication, and bearer management for UEs 115 served by base stations 105 associated with the EPC. User IP packets may be transferred through the S-GW, which itself may be connected to the P-GW. The P-GW may provide IP address allocation as well as other functions. The P-GW may be connected to the network operators IP services. The operators IP services may include access to the Internet, Intranet(s), an IP multimedia subsystem (IMS), or a packet-switched (PS) streaming service.

At least some of the network devices, such as a base station 105, may include subcomponents such as an access network entity, which may be an example of an access node controller (ANC). Each access network entity may communicate with UEs 115 through a number of other access network transmission entities, which may be referred to as a radio head, a smart radio head, or a transmission/reception point (TRP). In some configurations, various functions of each access network entity or base station 105 may be distributed across various network devices (e.g., radio heads and access network controllers) or consolidated into a single network device (e.g., a base station 105).

Wireless communications system 100 may operate using one or more frequency bands, typically in the range of 300 megahertz (MHz) to 300 gigahertz (GHz). Generally, the region from 300 MHz to 3 GHz is known as the ultra-high frequency (UHF) region or decimeter band, since the wavelengths range from approximately one decimeter to one meter in length. UHF waves may be blocked or redirected by buildings and environmental features. However, the waves may penetrate structures sufficiently for a macro cell to provide service to UEs 115 located indoors. Transmission of UHF waves may be associated with smaller antennas and shorter range (e.g., less than 100 km) compared to transmission using the smaller frequencies and longer waves of the high frequency (HF) or very high frequency (VHF) portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super high frequency (SHF) region using frequency bands from 3 GHz to 30 GHz, also known as the centimeter band. The SHF region includes bands such as the 5 GHz industrial, scientific, and medical (ISM) bands, which may be used opportunistically by devices that may be capable of tolerating interference from other users.

Wireless communications system 100 may also operate in an extremely high frequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz), also known as the millimeter band. In some examples, wireless communications system 100 may support millimeter wave (mmW) communications between UEs 115 and base stations 105, and EHF antennas of the respective devices may be even smaller and more closely spaced than UHF antennas. In some cases, this may facilitate use of antenna arrays within a UE 115. However, the propagation of EHF transmissions may be subject to even greater atmospheric attenuation and shorter range than SHF or UHF transmissions. Techniques disclosed herein may be employed across transmissions that use one or more different frequency regions, and designated use of bands across these frequency regions may differ by country or regulating body.

Wireless communications system 100 may include operations by different network operating entities (e.g., network operators), in which each network operator may share spectrum. In some instances, a network operating entity may be configured to use an entirety of a designated shared spectrum for at least a period of time before another network operating entity uses the entirety of the designated shared spectrum for a different period of time. Thus, in order to allow network operating entities use of the full designated shared spectrum, and in order to mitigate interfering communications between the different network operating entities, certain resources (e.g., time) may be partitioned and allocated to the different network operating entities for certain types of communication.

For example, a network operating entity may be allocated certain time resources reserved for exclusive communication by the network operating entity using the entirety of the shared spectrum. The network operating entity may also be allocated other time resources where the entity is given priority over other network operating entities to communicate using the shared spectrum. These time resources, prioritized for use by the network operating entity, may be utilized by other network operating entities on an opportunistic basis if the prioritized network operating entity does not utilize the resources. Additional time resources may be allocated for any network operator to use on an opportunistic basis.

Access to the shared spectrum and the arbitration of time resources among different network operating entities may be centrally controlled by a separate entity, autonomously determined by a predefined arbitration scheme, or dynamically determined based on interactions between wireless nodes of the network operators.

In various implementations, wireless communications system 100 may use both licensed and unlicensed radio frequency spectrum bands. For example, wireless communications system 100 may employ license assisted access (LAA), LTE-unlicensed (LTE-U) radio access technology, or NR technology in an unlicensed band (NR-U), such as the 5 GHz ISM band. In some cases, UE 115 and base station 105 of the wireless communications system 100 may operate in a shared radio frequency spectrum band, which may include licensed or unlicensed (e.g., contention-based) frequency spectrum. In an unlicensed frequency portion of the shared radio frequency spectrum band, UEs 115 or base stations 105 may traditionally perform a medium-sensing procedure to contend for access to the frequency spectrum. For example, UE 115 or base station 105 may perform a listen before talk (LBT) procedure such as a clear channel assessment (CCA) prior to communicating in order to determine whether the shared channel is available.

A CCA may include an energy detection procedure to determine whether there are any other active transmissions on the shared channel. For example, a device may infer that a change in a received signal strength indicator (RSSI) of a power meter indicates that a channel is occupied. Specifically, signal power that is concentrated in a certain bandwidth and exceeds a predetermined noise floor may indicate another wireless transmitter. A CCA also may include message detection of specific sequences that indicate use of the channel. For example, another device may transmit a specific preamble prior to transmitting a data sequence. In some cases, an LBT procedure may include a wireless node adjusting its own backoff window based on the amount of energy detected on a channel and/or the acknowledge/negative-acknowledge (ACK/NACK) feedback for its own transmitted packets as a proxy for collisions.

In general, four categories of LBT procedure have been suggested for sensing a shared channel for signals that may indicate the channel is already occupied. In a first category (CAT 1 LBT), no LBT or CCA is applied to detect occupancy of the shared channel. A second category (CAT 2 LBT), which may also be referred to as an abbreviated LBT, a single-shot LBT, or a 25-μs LBT, provides for the node to perform a CCA to detect energy above a predetermined threshold or detect a message or preamble occupying the shared channel. The CAT 2 LBT performs the CCA without using a random back-off operation, which results in its abbreviated length, relative to the next categories.

A third category (CAT 3 LBT) performs CCA to detect energy or messages on a shared channel, but also uses a random back-off and fixed contention window. Therefore, when the node initiates the CAT 3 LBT, it performs a first CCA to detect occupancy of the shared channel. If the shared channel is idle for the duration of the first CCA, the node may proceed to transmit. However, if the first CCA detects a signal occupying the shared channel, the node selects a random back-off based on the fixed contention window size and performs an extended CCA. If the shared channel is detected to be idle during the extended CCA and the random number has been decremented to 0, then the node may begin transmission on the shared channel. Otherwise, the node decrements the random number and performs another extended CCA. The node would continue performing extended CCA until the random number reaches 0. If the random number reaches 0 without any of the extended CCAs detecting channel occupancy, the node may then transmit on the shared channel. If at any of the extended CCA, the node detects channel occupancy, the node may re-select a new random back-off based on the fixed contention window size to begin the countdown again.

A fourth category (CAT 4 LBT), which may also be referred to as a full LBT procedure, performs the CCA with energy or message detection using a random back-off and variable contention window size. The sequence of CCA detection proceeds similarly to the process of the CAT 3 LBT, except that the contention window size is variable for the CAT 4 LBT procedure.

Use of a medium-sensing procedure to contend for access to an unlicensed shared spectrum may result in communication inefficiencies. This may be particularly evident when multiple network operating entities (e.g., network operators) are attempting to access a shared resource. In wireless communications system 100, base stations 105 and UEs 115 may be operated by the same or different network operating entities. In some examples, an individual base station 105 or UE 115 may be operated by more than one network operating entity. In other examples, each base station 105 and UE 115 may be operated by a single network operating entity. Requiring each base station 105 and UE 115 of different network operating entities to contend for shared resources may result in increased signaling overhead and communication latency.

In some cases, operations in unlicensed bands may be based on a carrier aggregation configuration in conjunction with component carriers operating in a licensed band (e.g., LAA). Operations in unlicensed spectrum may include downlink transmissions, uplink transmissions, peer-to-peer transmissions, or a combination of these. Duplexing in unlicensed spectrum may be based on frequency division duplexing (FDD), time division duplexing (TDD), or a combination of both.

In some examples, base station 105 or UE 115 may be equipped with multiple antennas, which may be used to employ techniques such as transmit diversity, receive diversity, multiple-input multiple-output (MIMO) communications, or beamforming. For example, wireless communications system 100 may use a transmission scheme between a transmitting device (e.g., a base station 105) and a receiving device (e.g., a UE 115), where the transmitting device is equipped with multiple antennas and the receiving device is equipped with one or more antennas. MIMO communications may employ multipath signal propagation to increase the spectral efficiency by transmitting or receiving multiple signals via different spatial layers, which may be referred to as spatial multiplexing. The multiple signals may, for example, be transmitted by the transmitting device via different antennas or different combinations of antennas. Likewise, the multiple signals may be received by the receiving device via different antennas or different combinations of antennas. Each of the multiple signals may be referred to as a separate spatial stream, and may carry bits associated with the same data stream (e.g., the same codeword) or different data streams. Different spatial layers may be associated with different antenna ports used for channel measurement and reporting. MIMO techniques include single-user MIMO (SU-MIMO) where multiple spatial layers are transmitted to the same receiving device, and multiple-user MIMO (MU-MIMO) where multiple spatial layers are transmitted to multiple devices.

Beamforming, which may also be referred to as spatial filtering, directional transmission, or directional reception, is a signal processing technique that may be used at a transmitting device or a receiving device (e.g., a base station 105 or a UE 115) to shape or steer an antenna beam (e.g., a transmit beam or receive beam) along a spatial path between the transmitting device and the receiving device. Beamforming may be achieved by combining the signals communicated via antenna elements of an antenna array such that signals propagating at particular orientations with respect to an antenna array experience constructive interference while others experience destructive interference. The adjustment of signals communicated via the antenna elements may include a transmitting device or a receiving device applying certain amplitude and phase offsets to signals carried via each of the antenna elements associated with the device. The adjustments associated with each of the antenna elements may be defined by a beamforming weight set associated with a particular orientation (e.g., with respect to the antenna array of the transmitting device or receiving device, or with respect to some other orientation).

In one example, a base station 105 may use multiple antennas or antenna arrays to conduct beamforming operations for directional communications with a UE 115. For instance, some signals (e.g. synchronization signals, reference signals, beam selection signals, or other control signals) may be transmitted by a base station 105 multiple times in different directions, which may include a signal being transmitted according to different beamforming weight sets associated with different directions of transmission. Transmissions in different beam directions may be used to identify (e.g., by the base station 105 or a receiving device, such as a UE 115) a beam direction for subsequent transmission and/or reception by the base station 105.

Some signals, such as data signals associated with a particular receiving device, may be transmitted by a base station 105 in a single beam direction (e.g., a direction associated with the receiving device, such as a UE 115). In some examples, the beam direction associated with transmissions along a single beam direction may be determined based at least in in part on a signal that was transmitted in different beam directions. For example, a UE 115 may receive one or more of the signals transmitted by the base station 105 in different directions, and the UE 115 may report to the base station 105 an indication of the signal it received with a highest signal quality, or an otherwise acceptable signal quality. Although these techniques are described with reference to signals transmitted in one or more directions by a base station 105, a UE 115 may employ similar techniques for transmitting signals multiple times in different directions (e.g., for identifying a beam direction for subsequent transmission or reception by the UE 115), or transmitting a signal in a single direction (e.g., for transmitting data to a receiving device).

A receiving device (e.g., a UE 115, which may be an example of a mmW receiving device) may try multiple receive beams when receiving various signals from the base station 105, such as synchronization signals, reference signals, beam selection signals, or other control signals. For example, a receiving device may try multiple receive directions by receiving via different antenna subarrays, by processing received signals according to different antenna subarrays, by receiving according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, or by processing received signals according to different receive beamforming weight sets applied to signals received at a plurality of antenna elements of an antenna array, any of which may be referred to as “listening” according to different receive beams or receive directions. In some examples a receiving device may use a single receive beam to receive along a single beam direction (e.g., when receiving a data signal). The single receive beam may be aligned in a beam direction determined based at least in part on listening according to different receive beam directions (e.g., a beam direction determined to have a highest signal strength, highest signal-to-noise ratio, or otherwise acceptable signal quality based at least in part on listening according to multiple beam directions).

In certain implementations, the antennas of a base station 105 or UE 115 may be located within one or more antenna arrays, which may support MIMO operations, or transmit or receive beamforming. For example, one or more base station antennas or antenna arrays may be co-located at an antenna assembly, such as an antenna tower. In some cases, antennas or antenna arrays associated with a base station 105 may be located in diverse geographic locations. A base station 105 may have an antenna array with a number of rows and columns of antenna ports that the base station 105 may use to support beamforming of communications with a UE 115. Likewise, a UE 115 may have one or more antenna arrays that may support various MIMO or beamforming operations.

In additional cases, UEs 115 and base stations 105 may support retransmissions of data to increase the likelihood that data is received successfully. HARQ feedback is one technique of increasing the likelihood that data is received correctly over a communication link 125. HARQ may include a combination of error detection (e.g., using a cyclic redundancy check (CRC)), forward error correction (FEC), and retransmission (e.g., automatic repeat request (ARQ)). HARQ may improve throughput at the MAC layer in poor radio conditions (e.g., signal-to-noise conditions). In some cases, a wireless device may support same-slot HARQ feedback, where the device may provide HARQ feedback in a specific slot for data received in a previous symbol in the slot, while in other cases, the device may provide HARQ feedback in a subsequent slot, or according to some other time interval.

Time intervals in LTE or NR may be expressed in multiples of a basic time unit, which may, for example, refer to a sampling period of T_(s)=1/30,720,000 seconds. Time intervals of a communications resource may be organized according to radio frames each having a duration of 10 milliseconds (ms), where the frame period may be expressed as T_(f)=307,200 T_(s). The radio frames may be identified by a system frame number (SFN) ranging from 0 to 1023. Each frame may include 10 subframes numbered from 0 to 9, and each subframe may have a duration of 1 ms. A subframe may be further divided into 2 slots each having a duration of 0.5 ms, and each slot may contain 6 or 7 modulation symbol periods (e.g., depending on the length of the cyclic prefix prepended to each symbol period). Excluding the cyclic prefix, each symbol period may contain 2048 sampling periods. In some cases, a subframe may be the smallest scheduling unit of the wireless communications system 100, and may be referred to as a transmission time interval (TTI). In other cases, a smallest scheduling unit of the wireless communications system 100 may be shorter than a subframe or may be dynamically selected (e.g., in bursts of shortened TTIs (sTTIs) or in selected component carriers using sTTIs).

In some wireless communications systems, a slot may further be divided into multiple mini-slots containing one or more symbols. In some instances, a symbol of a mini-slot or a mini-slot may be the smallest unit of scheduling. Each symbol may vary in duration depending on the subcarrier spacing or frequency band of operation, for example. Further, some wireless communications systems may implement slot aggregation in which multiple slots or mini-slots are aggregated together and used for communication between a UE 115 and a base station 105.

The term “carrier,” as may be used herein, refers to a set of radio frequency spectrum resources having a defined physical layer structure for supporting communications over a communication link 125. For example, a carrier of a communication link 125 may include a portion of a radio frequency spectrum band that is operated according to physical layer channels for a given radio access technology. Each physical layer channel may carry user data, control information, or other signaling. A carrier may be associated with a pre-defined frequency channel (e.g., an evolved universal mobile telecommunication system terrestrial radio access (E-UTRA) absolute radio frequency channel number (EARFCN)), and may be positioned according to a channel raster for discovery by UEs 115. Carriers may be downlink or uplink (e.g., in an FDD mode), or be configured to carry downlink and uplink communications (e.g., in a TDD mode). In some examples, signal waveforms transmitted over a carrier may be made up of multiple sub-carriers (e.g., using multi-carrier modulation (MCM) techniques such as orthogonal frequency division multiplexing (OFDM) or discrete Fourier transform spread OFDM (DFT-S-OFDM)).

The organizational structure of the carriers may be different for different radio access technologies (e.g., LTE, LTE-A, LTE-A Pro, NR). For example, communications over a carrier may be organized according to TTIs or slots, each of which may include user data as well as control information or signaling to support decoding the user data. A carrier may also include dedicated acquisition signaling (e.g., synchronization signals or system information, etc.) and control signaling that coordinates operation for the carrier. In some examples (e.g., in a carrier aggregation configuration), a carrier may also have acquisition signaling or control signaling that coordinates operations for other carriers.

Physical channels may be multiplexed on a carrier according to various techniques. A physical control channel and a physical data channel may be multiplexed on a downlink carrier, for example, using time division multiplexing (TDM) techniques, frequency division multiplexing (FDM) techniques, or hybrid TDM-FDM techniques. In some examples, control information transmitted in a physical control channel may be distributed between different control regions in a cascaded manner (e.g., between a common control region or common search space and one or more UE-specific control regions or UE-specific search spaces).

A carrier may be associated with a particular bandwidth of the radio frequency spectrum, and in some examples the carrier bandwidth may be referred to as a “system bandwidth” of the carrier or the wireless communications system 100. For example, the carrier bandwidth may be one of a number of predetermined bandwidths for carriers of a particular radio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). In some examples, each served UE 115 may be configured for operating over portions or all of the carrier bandwidth. In other examples, some UEs 115 may be configured for operation using a narrowband protocol type that is associated with a predefined portion or range (e.g., set of subcarriers or RBs) within a carrier (e.g., “in-band” deployment of a narrowband protocol type).

In a system employing MCM techniques, a resource element may consist of one symbol period (e.g., a duration of one modulation symbol) and one subcarrier, where the symbol period and subcarrier spacing are inversely related. The number of bits carried by each resource element may depend on the modulation scheme (e.g., the order of the modulation scheme). Thus, the more resource elements that a UE 115 receives and the higher the order of the modulation scheme, the higher the data rate may be for the UE 115. In MIMO systems, a wireless communications resource may refer to a combination of a radio frequency spectrum resource, a time resource, and a spatial resource (e.g., spatial layers), and the use of multiple spatial layers may further increase the data rate for communications with a UE 115.

Devices of the wireless communications system 100 (e.g., base stations 105 or UEs 115) may have a hardware configuration that supports communications over a particular carrier bandwidth, or may be configurable to support communications over one of a set of carrier bandwidths. In some examples, the wireless communications system 100 may include base stations 105 and/or UEs 115 that support simultaneous communications via carriers associated with more than one different carrier bandwidth.

Wireless communications system 100 may support communication with a UE 115 on multiple cells or carriers, a feature which may be referred to as carrier aggregation or multi-carrier operation. A UE 115 may be configured with multiple downlink component carriers and one or more uplink component carriers according to a carrier aggregation configuration. Carrier aggregation may be used with both FDD and TDD component carriers.

In some cases, wireless communications system 100 may utilize enhanced component carriers (eCCs). An eCC may be characterized by one or more features including wider carrier or frequency channel bandwidth, shorter symbol duration, shorter TTI duration, or modified control channel configuration. In certain instances, an eCC may be associated with a carrier aggregation configuration or a dual connectivity configuration (e.g., when multiple serving cells have a suboptimal or non-ideal backhaul link). An eCC may also be configured for use in unlicensed spectrum or shared spectrum (e.g., where more than one operator is allowed to use the spectrum, such as NR-shared spectrum (NR-SS)). An eCC characterized by wide carrier bandwidth may include one or more segments that may be utilized by UEs 115 that are not capable of monitoring the whole carrier bandwidth or are otherwise configured to use a limited carrier bandwidth (e.g., to conserve power).

In additional cases, an eCC may utilize a different symbol duration than other component carriers, which may include use of a reduced symbol duration as compared with symbol durations of the other component carriers. A shorter symbol duration may be associated with increased spacing between adjacent subcarriers. A device, such as a UE 115 or base station 105, utilizing eCCs may transmit wideband signals (e.g., according to frequency channel or carrier bandwidths of 20, 40, 60, 80 MHz, etc.) at reduced symbol durations (e.g., 16.67 microseconds). A TTI in eCC may consist of one or multiple symbol periods. In some cases, the TTI duration (that is, the number of symbol periods in a TTI) may be variable.

Wireless communications system 100 may be an NR system that may utilize any combination of licensed, shared, and unlicensed spectrum bands, among others. The flexibility of eCC symbol duration and subcarrier spacing may allow for the use of eCC across multiple spectrums. In some examples, NR shared spectrum may increase spectrum utilization and spectral efficiency, specifically through dynamic vertical (e.g., across the frequency domain) and horizontal (e.g., across the time domain) sharing of resources.

FIG. 2 shows a block diagram of a design of a base station 105 and a UE 115, which may be one of the base station and one of the UEs in FIG. 1. At base station 105, a transmit processor 220 may receive data from a data source 212 and control information from a controller/processor 240. The control information may be for the PBCH, PCFICH, PHICH, PDCCH, EPDCCH, MPDCCH etc. The data may be for the PDSCH, etc. The transmit processor 220 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The transmit processor 220 may also generate reference symbols, e.g., for the PSS, SSS, and cell-specific reference signal. A transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators/demodulators 232 a through 232 t. Each modulator/demodulator 232 may process a respective output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each modulator/demodulator 232 may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators/demodulators 232 a through 232 t may be transmitted via the antennas 234 a through 234 t, respectively.

At UE 115, the antennas 252 a through 252 r may receive the downlink signals from the base station 105 and may provide received signals to the modulators/demodulators 254 a through 254 r, respectively. Each modulator/demodulator 254 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each modulator/demodulator 254 may further process the input samples (e.g., for OFDM, etc.) to obtain received symbols. A MIMO detector 256 may obtain received symbols from all the modulators/demodulators 254 a through 254 r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 258 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 115 to a data sink 260, and provide decoded control information to a controller/processor 280.

On the uplink, at the UE 115, a transmit processor 264 may receive and process data (e.g., for the PUSCH) from a data source 262 and control information (e.g., for the PUCCH) from the controller/processor 280. The transmit processor 264 may also generate reference symbols for a reference signal. The symbols from the transmit processor 264 may be precoded by a TX MIMO processor 266 if applicable, further processed by the modulators/demodulators 254 a through 254 r (e.g., for SC-FDM, etc.), and transmitted to the base station 105. At the base station 105, the uplink signals from the UE 115 may be received by the antennas 234, processed by the modulators/demodulators 232, detected by a MIMO detector 236 if applicable, and further processed by a receive processor 238 to obtain decoded data and control information sent by the UE 115. The processor 238 may provide the decoded data to a data sink 239 and the decoded control information to the controller/processor 240.

The controllers/processors 240 and 280 may direct the operation at the base station 105 and the UE 115, respectively. The controller/processor 240 and/or other processors and modules at the base station 105 may perform or direct the execution of various processes for the techniques described herein. The controllers/processor 280 and/or other processors and modules at the UE 115 may also perform or direct the execution of the functional blocks illustrated in FIG. 3, and/or other processes for the techniques described herein. The memories 242 and 282 may store data and program codes for the base station 105 and the UE 115, respectively. A scheduler 244 may schedule UEs for data transmission on the downlink and/or uplink.

In NR or NR-U operations, a scheduling request (SR) may be periodically configured via uplink control signaling, (e.g., PUCCH) to give the UE an opportunity to request resources for uplink transmissions. However, in NR operations defined in 3GPP Release 15 (Rel. 15), the SR can be cancelled via signaling such as a slot format indication (SFI), downlink control information (DCI). An SR may be cancelled when the SFI indicates the SR symbols to configured as either flexible or downlink symbols. An SF may also be cancelled when the UE receives a downlink grant to receive in the SR-configured symbols. In NR-U operations defined in 3GPP Release 16 (Rel. 16), the SR can further be cancelled if the UE does not have access to the shared communication channel, such as when the UE detects an unsuccessful LBT procedure for accessing the shared channel. Additionally, when a DCI format 2_0 is configured but not detected by the UE, the configured SR will be cancelled. If there is chance that the configured SR cannot be transmitted, there may be a negative impact to the UE's uplink traffic transmission. When the UE cannot send an SR, the UE will not be granted uplink resources for the transmission.

In an effort to provide a UE with additional chances for transmitting SR, prior transmission technologies (e.g., MulteFire) have allowed the UE to send SR in the special subframe at the beginning of an uplink burst in a given transmission opportunity. However, neither NR nor NR-U operations define a special subframe. Moreover, the more rigid structure defined in the special subframe opportunity may not fit within the more flexible nature of NR and NR-U operations. Accordingly, various aspects of the present disclosure are directed to an on-demand or triggered SR, in which the UE is preconfigured with triggered SR resources for triggered SR transmissions. Compatible UEs may further be configured to monitor for a trigger signal, which triggers the UE to use such triggered SR resources for SR transmissions.

FIG. 3 is a block diagram illustrating example blocks executed by a UE to implement one aspect of the present disclosure. The example blocks will also be described with respect to UE 115 as illustrated in FIGS. 2 and 6. FIG. 6 is a block diagram illustrating UE 115 configured according to one aspect of the present disclosure. UE 115 includes the structure, hardware, and components as illustrated for UE 115 of FIG. 2. For example, UE 115 includes controller/processor 280, which operates to execute logic or computer instructions stored in memory 282, as well as controlling the components of UE 115 that provide the features and functionality of UE 115. UE 115, under control of controller/processor 280, transmits and receives signals via wireless radios 600 a-r and antennas 252 a-r. Wireless radios 600 a-r includes various components and hardware, as illustrated in FIG. 2 for UE 115, including modulator/demodulators 254 a-r, MIMO detector 256, receive processor 258, transmit processor 264, and TX MIMO processor 266.

At block 300, a UE receives a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered SR transmission. The UE, such as UE 115, under control of controller/processor 280, executes triggered SR logic 601, stored in memory 282. The functionality and actions enabled by execution of the code and instructions of triggered SR logic 601 (referred to as the “execution environment” of triggered SR logic 601) provides for UE 115 to recognize the control signaling that configure UE 115 with triggered SR resources. UE 115 may then store the configured resources in memory 282 at T-SR resources 602. The triggered SR resources may be configured either as a fixed resource or pool of resources that UE 115 may select, such as via a selection process, such as a selection sequence, hashing procedure, or the like, that will be known to both UE 115 and the serving base station.

At block 301, the UE monitors for a trigger signal triggering transmission of a triggered SR. UE 115 may further be configured for the on-demand or triggered SR procedure by the serving base station. Further within the execution environment of triggered SR logic 601, UE 115 would recognize the configuration signaling, received via antennas 252 a-r and wireless radios 600 a-r, that identifies to UE 115 a bit field within a particular control signal where a trigger signal would be located for conducting the triggered SR transmission. UE 115 monitors for the identified bit field for the trigger signal.

At block 302, the UE transmits the triggered SR using the transmission resource in response to detecting the trigger signal. For UE 115, which is configured for on-demand or triggered SR operations within the execution environment of triggered SR logic 601, when the trigger signal is detected in the identified bit field, UE 115 may then transmit a triggered SR in the preconfigured triggered SR resources. When UE 115 detects data in data buffer 603, in memory 282, it may use the triggered SR resource selected from T-SR resources for transmitting an SR to obtain an uplink grant for transmitting the data.

FIG. 4 is a block diagram illustrating an NR-U network 40 having UEs 115 a and 115 h-115 j in communication with base station 105 and configured for on-demand or triggered SR according to aspects of the present disclosure. UEs 115 a and 115 h-115 j communicate with base station 105 via a shared communication channel. Transmission streams 400-403 represent the communications over the shared communication channel from UEs 115 a and 115 h-115 j, respectively. At 405, base station 105 transmits a configuration message to UEs 115 a and 115 h-115 j configuring the UEs for on-demand or triggered SR operations. The configuration message at 405 configures UEs 115 a and 115 h-115 j with the identification of a bit field within a control message (e.g., PDCCH, group common (GC)-PDCCH, etc.) that would contain a trigger signal. For example, the configuration message at 405 from base station 105 configures the UEs 115 a and 115 h-115 j with the radio network temporary identifier (RNTI) for the GC-PDCCH, which search space the UEs are to search, and which bit field within the GC-PDCCH will contain the SR trigger signal. As illustrated, the same trigger bit can be configured for multiple UEs so they transmit the SRs together.

A configuration message at 405 may also configure the trigger SR resources for UEs 115 a and 115 h-115 j. The trigger SR resources may be configured as a fixed resource, as illustrated for triggered SR resources, T-SR 411, 413, 414, 418, 420, 421, 425, 427, 428, 432, 434, and 435. UEs 115 a and 115 h-115 j would then monitor for the bit field in the control message identified in the configuration message at 405.

Base station 105 transmits the control message at 406. The control message at 406 may include, for example, the PDCCH or GC-PDCCH with the bit field that UEs 115 a and 115 h-115 j are monitoring for the trigger signal. In addition to the trigger signal, the bit field can provide a timing indication for SR transmission. Such a timing indication may include offset 407, which may indicate a slot offset from the control message (e.g., GC-PDCCH) at 406 to the trigger SR, T-SR 411. For example, offset 407 may be signaled in the form of a K2 offset indication instead of a fixed offset from the control message at 406.

It should be noted that base station 105 may transmit the trigger signal dynamically in order to trigger UE 115 to use a next triggered SR resource when UE 115 has experienced some canceled scheduled SR occasions. In additional or alternative aspects, base station 105 may semi-persistently initiate UE 115 to begin using the triggered SR resources.

It should be noted that, in additional or alternative aspects of the present disclosure, other information can also be provided, within the configuration message at 405 or in the control message at 406.

Different options may be implemented to trigger a UE to actually use the triggered SR resource for SR transmissions. With multiple UEs each available to send such SR transmissions, there may be occasions where transmission collisions or congestion may occur with multiple UEs each trying to use the triggered SR resources for the SR transmissions. In a first optional implementation, all UEs configured to monitor the bit field in the control message are eligible for transmission if the bit field indicates a trigger signal. For example, because each of UEs 115 a and 115 h-115 j have been configured for on-demand or triggered SR operations at 405, each of UEs 115 a and 115 h-115 j are eligible to use the preconfigured triggered SR resources for SR transmission. This optional implementation may be useful for a case that the SR trigger is provided as an additional opportunity for SR reporting. It may also be possible that a UE is not configured with SR opportunities in the beginning, so all SR opportunities are triggered.

In a second optional implementation, the UEs that are eligible for using the triggered SR resources for SR transmissions are the ones of UEs 115 a and 115 h-115 j that are both configured for on-demand or triggered SR and have experienced cancelation of a preconfigured number of configured SR occasions within a window, such as window 404. Base station 105 may configured UEs 115 a and 115 h-115 j with the length of window 404 in either the configuration message at 405 or the control message at 406. As illustrated, window 404 extends beyond the triggered SR resources, T-SR 411, 418, 425, and 432. Accordingly, a UE with an SR opportunity within window 404 in the future can transmit as well. UEs 115 a and 115 h-115 j can assume the future SR opportunities will be cancelled, such that the later opportunities may be polled in the triggered SR resource, T-SR 411, 418, 425, and 432.

For example, where a threshold number of three canceled SR occasions within window 404 is set for performing triggered SR transmissions, as the trigger signal is detected by UE 115 i, UE 115 i has only experienced two canceled SR occasions at C-SRs 422 and 423. Because the window 404 extends beyond the triggered resource, T-SR 425, UE 115 i may continue to monitor configured SR occasions. Thus, as UE 115 i experiences a third canceled configured SR occasion at C-SR 424 after the trigger signal at 406, it may then be eligible to use T-SR 425.

In a further example, UE 115 a is able to transmit SR at T-SR 411 and, therefore, assumes the next configured SR occasion within window 404 at C-SR 412 is canceled or actively unschedules the occasion at C-SR 412. UE 115 h detects failure of an LBT procedure for access to the shared communication channel and, thus, cannot transmit SR at T-SR 418. In such an instance, UE 115 h may be allowed to transmit SR at C-SR 419 within window 404. Similar to UE 115 a, UE 115 i unschedules C-SR 426 after successfully transmitting SR at T-SR 425, and similar to UE 115 h, UE 115 j does not have access to the shared channel and cannot send an SR at T-SR 432. However, UE 115 j also cannot successfully complete an LBT for access to the shared channel for transmitting SR at C-SR 433.

According to the second optional implementation, before any of UEs 115 a and 115 h-115 j would attempt to transmit SR at the triggered SR resource, T-SR 411, 418, 425, and 432, each would determine whether they had experienced configured SR cancelations up to the preconfigured threshold number. This may be beneficial for the case where the triggered SR resources are provided for compensating SR resources. Base station 105 would have good knowledge of which of UEs 115 a and 115 h-115 j experienced canceled configured SR occasions, such as by previous SFI or DCI-based cancellations, or due to any of UEs 115 a or 115 h-115 j being outside of an available channel occupancy time (COT), where such UE is not configured to transmitting SR outside of an available COT.

FIG. 5 is a block diagram illustrating an NR-U network 40 having UEs 115 a and 115 h-115 j in communication with base station 105 and configured for on-demand or triggered SR according to aspects of the present disclosure. UEs 115 a and 115 h-115 i communicate with base station 105 via a shared communication channel. Transmission streams 500-502 represent the communications over the shared communication channel from UEs 115 a and 115 h-115 i, respectively. At 504, base station 105 transmits a configuration message to UEs 115 a and 115 h-115 i configuring the UEs for on-demand or triggered SR operations, as described above with respect to FIG. 4. The configuration message at 504 configures UEs 115 a and 115 h-115 i with the identification of a bit field within a control message (e.g., PDCCH, group common (GC)-PDCCH, etc.) that would contain a trigger signal.

A configuration message at 405 may also configure the triggered SR resources for UEs 115 a and 115 h-115 i. Instead of fixed resources, as described in the aspect illustrated in FIG. 4, the trigger SR resources of FIG. 5 are configured as a pool of multiple triggered SR resources, T-SR pool 507. T-SR pool 507 includes multiple candidate triggered SR resources that may be selected by UEs 115 a and 115 h-115 i for triggered SR transmissions. It should be noted that, while T-SR pool 507 includes identification of three resources, labeled A, B, and C, it should be understood that T-SR pool 507 may include more than three candidate resources. The labeled pool resources, A, B, C, are included for ease of description.

As illustrated in FIG. 5, UEs 115 a and 115 h-115 i determine a number of canceled configured SR occasions, C-SR, over window 503. The length of window 503 is configured before the triggered SR resource, T-SR pool 507. Thus, the ones of UEs 115 a and 115 h-115 i that have experienced cancelled configured SR occasions over a preconfigured threshold number may be eligible for using the triggered SR resources for SR transmissions. Thus, in an example implementation where a UE would have to experience two or more canceled configured SR occasions, UEs 115 h and 115 i would be eligible, while UE 115 a would not. In an example implementation where a UE would have to experience one canceled configured SR occasion, each of UEs 115 a and 115 h-115 i would be eligible.

With the triggered SR resources defined as a pool of resources, T-SR pool 507, UEs 115 a and 115 h-115 i may use a preconfigured procedure to select the resource for the triggered SR transmission from T-SR pool 507. Such a preconfigured procedure would also be known to base station 105. In one example implementation, the preconfigured procedure may be a selection pattern known to each of UEs 115 a and 115 h-115 i and base station 105. In another example implementation, the preconfigured procedure may be a hash procedure known to each of UEs 115 a and 115 h-115 i and base station 105.

At 505, base station 105 transmits the control message that includes the bit field for which UEs 115 a and 115 h-115 i are monitoring for a trigger signal. If such a trigger signal is detected in the control message, UEs 115 a and 115 h-115 i may determine whether to actually use one of the triggered SR resources of T-SR pool 507 to transmit an SR. As indicated above, the bit field may further include a offset, such as offset 506, which identifies the offset from the control message at 506 that UEs 115 a and 115 h-115 i may transmit on the triggered SR resource. As the trigger signal is detected and UEs 115 a and 115 h-115 i determine to use triggered SR resource, each of UEs 115 a and 115 h-115 i may performing the hashing sequence to select a resource from T-SR pool 507. For example, UE 115 a may hash to resource A of the first instance of T-SR pool 507 on transmission stream 500, and to resource C of the second instance of T-SR pool 507. UE 115 h may hash to resource C of the first instance of T-SR pool 507 on transmission stream 501, and to resource A of the second instance of T-SR pool 507. UE 115 i may also collide with UE 115 h by hashing to resource C of the first instance of T-SR pool 507 on transmission stream 502. UE 115 i determines that it is not eligible to use the triggered SR resource of the second instance of T-SR pool 507 and does not perform the hashing.

As illustrated with respect to UEs 115 h and 115 i, there is a chance for multiple UEs to hash to the same resource. In order to address such collision, a hashing seed or hashing control may be included in the bit field with SR trigger signal to affect the UE's hashing rule. Such a hashing seed or control provided to UEs 115 h and 115 i may allow each such UE to hash to a different resource of T-SR pool 507. In other words, the hashing results will be different under different hashing seed, so it is likely, by choosing the proper hashing seed, the number of collision events can be reduced or removed.

In order to control congestion of UEs attempting to transmit SR using the triggered SR resources, additional aspects may include additional factors for each eligible UE to consider before transmitting SR using the triggered SR resources, whether fixed (FIG. 4) or pooled (FIG. 5). According to one example aspect, each of UEs 115 a and 115 h-115 i generate a random variable to compare against a preconfigured threshold value. When the random variable meets the threshold value, the UE can transmit using the triggered SR resources, while, when the random variable fails to meet the threshold, the UE cannot transmit using the triggered SR resources. The random variable may be generated as a pseudo-random value, such that both base station 105 and UEs 115 a and 115 h-115 i would be able to arrive at the same pseudo-random value. The random variable procedure may further be useful when there are too many UEs eligible for the triggered SR resource pool to transmit without causing multiple collisions.

According to another example aspect, it may not be urgent for a UE to transmit SR quickly, such that the UE can afford a few cancellations of SR occasions. Thus, after determining their eligibility for accessing T-SR pool 507 for SR transmissions, each of UEs 115 a and 115 h-115 i then determine whether the number of configured SR opportunity cancelations it has experienced. This calculation of canceled configured SR occasions is different than the determination of the number of canceled configured SR occasions to determine eligibility according to the previously-described example aspect. For example, the number may be predetermined at two or more cancelations. Accordingly, after each of UEs 115 a and 115 h-115 i have determined their eligibility to access T-SR pool 507, UE 115 h and 115 i each determine that they have experienced two cancelations (C-SR 512-513 and 516-517) and, thus, may select a resource of T-SR pool 507 for triggered SR transmissions. However, UE 115 a determines that it has only experienced one cancelation at C-SR 509 and one successful SR transmission at C-SR 508. Therefore, UE 115 a determines that it will not select a resource from T-SR pool 507 to attempt a triggered SR transmission. Instead, UE 115 a may attempt SR transmission at C-SR 510.

According to another example aspect, UEs 115 a and 115 h-115 i may determine whether to use triggered SR transmission according to the transmission priority of the uplink transmission. The SR also has different priority depending on the associated logic channel. Thus, base station 105 may trigger the SR based on the priority associated with the corresponding UE. For example, UEs 115 a and 115 h-115 i may determine their transmission priority before selecting a resource from T-SR pool 507. In one scenario, UE 115 a and 115 i may have a priority higher than a predefined level and, thus, may select a resource from T-SR pool 507 for triggered SR transmission. The priority threshold can be RRC configured by base station 105 or may be included in the bit field of the control message for the SR trigger signal.

In each of the example aspects for managing congestion of the triggered SR resources, after UEs 115 a and 115 h-115 i detect the trigger signal in the control message at 505, UEs 115 a and 115 h-115 i may unschedule or cancel the current configured SR occasions, C-SR 510, 511, 514, 515, 518, and 519, after window 503. However, where any of UEs 115 a and 115 h-115 i determine it should not use triggered SR resources, the UE may use the unscheduled configured SR resource for SR transmissions.

When transmitting the triggered SR according to the various aspects of the present disclosure. The SR transmission will not be multiplexed with any other feedback, such as channel state information (CSI), hybrid automatic receive request (HARQ) acknowledgement information, and the like. In this way, the uplink format for the control transmission (e.g., PUCCH) will be the same for all UEs and, thus, easier to plan the resources. For example, PUCCH format 0 or 1 may be used to carry one bit only for SR.

Additionally, a triggered SR resource pool, such as T-SR pool 507 is configured as a time/frequency domain PUCCH resource with either a cyclic shift or a pair of cyclic shifts. In one optional implementation with a single cyclic shift, the UE, such as one or more of UEs 115 a and 115 h-115 i would only transmit when a request for resources is being made with the SR transmission. In a second optional implementation with a pair of cyclic shifts, the UE, such as one or more of UEs 115 a and 115 h-115 i can transmit a positive SR, when resources are requested for uplink transmission, or a negative SR, when the UE does not have data in the buffer for uplink transmission and it, therefore, not requesting transmission resources.

In current NR behavior, if a UE is not configured with SR resources, the UE will use physical random access channel (PRACH) to request uplink resources. Referring back to FIG. 4, where a UE, such as UE 115 j, is configured with triggered SR resources (e.g., T-SR 432, 434, and 435, UE 115 j may fall back to use PRACH 436, when there have been no successful opportunities for SR transmission over threshold period 437. As experienced by UE 115 j, each SR occasion has either been canceled or unsuccessful, C-SR 429-431 and T-SR 432, 434, and 435, or unscheduled, C-SR 433. The threshold length of threshold period 437 can be RRC configured or hard coded.

It should be noted that such fall back to PRACH after a preconfigured threshold can be further extended even if triggered SR resources are not configured. If configured SR opportunities have been cancelled or unsuccessful for such a fall back threshold, the UE may fall back to using PRACH for request of resources for transmission.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

The functional blocks and modules in FIG. 3 may comprise processors, electronics devices, hardware devices, electronics components, logical circuits, memories, software codes, firmware codes, etc., or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the disclosure herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present disclosure. Skilled artisans will also readily recognize that the order or combination of components, methods, or interactions that are described herein are merely examples and that the components, methods, or interactions of the various aspects of the present disclosure may be combined or performed in ways other than those illustrated and described herein.

The various aspects of the present disclosure may be implemented in many different ways, including methods, processes, non-transitory computer-readable medium having program code recorded thereon, apparatus having one or more processors with configurations and instructions for performing the described features and functionality, and the like. A first aspect configured for wireless communication includes receiving, by a UE, a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered SR transmission, monitoring, by the UE, for a trigger signal triggering transmission of a triggered SR, and transmitting, by the UE, the triggered SR using the transmission resource in response to detecting the trigger signal.

A second aspect, alone or in combination with a first aspect, further including receiving, at the UE, a triggered SR configuration message that identifies a bit field within a control signal of the serving base station for the monitoring for the trigger signal.

A third aspect, alone or in combination with the second aspect, wherein the trigger signal includes a timing indication for the triggered SR transmission.

A fourth aspect, alone or in combination with the third aspect, wherein the timing indication includes one of a fixed transmission time; or a slot offset from the trigger signal.

A fifth aspect, alone or in combination with the second aspect, further including: receiving, by the UE, a window length parameter, wherein the window length parameter is received in one of: the triggered SR configuration message or the bit field for the trigger signal; and determining, by the UE, cancellation of one or more configured SR opportunities within a window length determined by the window length parameter, wherein the transmitting the triggered SR is further in response to determination of the cancellation of the one or more configured SR opportunities within the window length.

A sixth aspect, alone or in combination with the fifth aspect, wherein the window length is positioned one of: prior to transmission of the triggered SR; or over a time including at least one future configured SR transmission opportunity.

A seventh aspect, alone or in combination with the sixth aspect, further including: canceling the at least one future configured SR transmission opportunity within the window length.

An eighth aspect, alone or in combination with the second aspect, wherein the transmission resource includes one of: a fixed resource for the triggered SR transmission; or a selected resource from a pool of transmission resources.

A ninth aspect, alone or in combination with the eighth aspect, further including: selecting, by the UE, the transmission resource from the pool of transmission resources using a hashing rule know to the UE and the serving base station.

A tenth aspect, alone or in combination with the ninth aspect, further including: receiving, by the UE, a hashing seed within the bit field, wherein the UE uses the hashing seed with the hashing rule for the selecting the transmission resource.

An eleventh aspect, alone or in combination with the eighth aspect, wherein each resource of the pool of transmission resources is configured with a time-frequency domain resource and one of: a single cyclic shift or a pair of cyclic shifts.

A twelfth aspect, alone or in combination with the eleventh aspect, wherein, when the transmission resource is configured with the single cyclic shift, the transmitting includes: transmitting a positive SR in the triggered SR, in response to a request for scheduling uplink transmission; and refraining from transmission of the triggered SR for a negative SR, in response to indicating no data for uplink transmission.

A thirteenth aspect, alone or in combination with the eleventh aspect, wherein, when the transmission resource is configured with the pair of cyclic shifts, the transmitting includes: transmitting a positive SR in the triggered SR, in response to a request for scheduling uplink transmission; and transmitting a negative SR in the triggered SR, in response to indicating no data for uplink transmission.

A fourteenth aspect, alone or in combination with the second aspect, further including: generating, by the UE, a pseudo-random variable known to the UE and the serving base station; comparing, by the UE, the pseudo-random variable to a preconfigured threshold, wherein the transmitting is conducted in response to the pseudo-random variable falling within the preconfigured threshold; and refraining, by the UE, from transmission of the triggered SR in response to the pseudo-random variable exceeding the preconfigured threshold.

A fifteenth aspect, alone or in combination with the second aspect, further including: determining, by the UE, a total number of cancelled configured SR transmissions that have been canceled over a predefined period, wherein the transmitting is conducted in response to the total number of cancelled configured SR transmissions exceeds a predetermined threshold; and refraining, by the UE, from transmission of the triggered SR in response to the total number of cancelled configured SR transmissions is less than the predetermined threshold.

A sixteenth aspect, alone or in combination with the second aspect, further including: comparing, by the UE, a transmission priority associated with a SR to a predetermined priority threshold, wherein the transmitting is conducted in response to the transmission priority exceeding the predetermined priority threshold; and refraining, by the UE, from transmission of the triggered SR in response to the transmission priority falling below the predetermined priority threshold.

A seventeenth aspect, alone or in combination with the sixteenth aspect, further including: receiving, by the UE, the predetermined priority threshold via one of: a RRC configuration message or the bit field.

An eighteenth aspect, alone or in combination with the second aspect, wherein the transmitting includes: transmitting the triggered SR without other CSI and acknowledgement signals multiplexed therewith.

A nineteenth aspect, alone or in combination with the first aspect, further including: determining, by the UE, availability of transmission of the triggered SR on the transmission resource, wherein the transmitting occurs in response to a determination of transmission availability; and refraining, by the UE, from transmission of the triggered SR in response to a determination of transmission unavailability.

A twentieth aspect, alone or in combination with the nineteenth aspect, further including: determining, by the UE, no successful SR transmissions over a predefined window of time; and performing, by the UE, a random access request procedure for an uplink transmission grant, in response to the determining the no successful SR transmissions.

A twenty-first aspect, alone or in combination with the twentieth aspect, wherein the predefined window of time is one of: precoded into the UE; or received by the UE via control signaling from the serving base station.

A twenty-second aspect including any combination of the first through the twenty-first aspects.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure herein may be implemented or performed with a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

In one or more exemplary designs, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. Computer-readable storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. Also, a connection may be properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, or digital subscriber line (DSL), then the coaxial cable, fiber optic cable, twisted pair, or DSL, are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

As used herein, including in the claims, the term “and/or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and/or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Also, as used herein, including in the claims, “or” as used in a list of items prefaced by “at least one of” indicates a disjunctive list such that, for example, a list of “at least one of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., A and B and C) or any of these in any combination thereof.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. 

What is claimed is:
 1. A method of wireless communication, comprising: receiving, by a user equipment (UE), a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered scheduling request (SR) transmission; monitoring, by the UE, for a trigger signal triggering transmission of a triggered SR; and transmitting, by the UE, the triggered SR using the transmission resource in response to detecting the trigger signal.
 2. The method of claim 1, further including: receiving, at the UE, a triggered SR configuration message that identifies a bit field within a control signal of the serving base station for the monitoring for the trigger signal.
 3. The method of claim 2, wherein the trigger signal includes a timing indication for the triggered SR transmission.
 4. The method of claim 3, wherein the timing indication includes one of: a fixed transmission time; or a slot offset from the trigger signal.
 5. The method of claim 2, further including: receiving, by the UE, a window length parameter, wherein the window length parameter is received in one of: the triggered SR configuration message or the bit field for the trigger signal; and determining, by the UE, cancellation of one or more configured SR opportunities within a window length determined by the window length parameter, wherein the transmitting the triggered SR is further in response to determination of the cancellation of the one or more configured SR opportunities within the window length.
 6. The method of claim 5, wherein the window length is positioned one of: prior to transmission of the triggered SR; or over a time including at least one future configured SR transmission opportunity.
 7. The method of claim 6, further including: canceling the at least one future configured SR transmission opportunity within the window length.
 8. The method of claim 2, wherein the transmission resource includes one of: a fixed resource for the triggered SR transmission; or a selected resource from a pool of transmission resources.
 9. The method of claim 8, further including: selecting, by the UE, the transmission resource from the pool of transmission resources using a hashing rule know to the UE and the serving base station.
 10. The method of claim 9, further including: receiving, by the UE, a hashing seed within the bit field, wherein the UE uses the hashing seed with the hashing rule for the selecting the transmission resource.
 11. The method of claim 8, wherein each resource of the pool of transmission resources is configured with a time-frequency domain resource and one of: a single cyclic shift or a pair of cyclic shifts.
 12. The method of claim 11, wherein, when the transmission resource is configured with the single cyclic shift, the transmitting includes: transmitting a positive SR in the triggered SR, in response to a request for scheduling uplink transmission; and refraining from transmission of the triggered SR for a negative SR, in response to indicating no data for uplink transmission.
 13. The method of claim 11, wherein, when the transmission resource is configured with the pair of cyclic shifts, the transmitting includes: transmitting a positive SR in the triggered SR, in response to a request for scheduling uplink transmission; and transmitting a negative SR in the triggered SR, in response to indicating no data for uplink transmission.
 14. The method of claim 2, further including: generating, by the UE, a pseudo-random variable known to the UE and the serving base station; comparing, by the UE, the pseudo-random variable to a preconfigured threshold, wherein the transmitting is conducted in response to the pseudo-random variable falling within the preconfigured threshold; and refraining, by the UE, from transmission of the triggered SR in response to the pseudo-random variable exceeding the preconfigured threshold.
 15. The method of claim 2, further including: determining, by the UE, a total number of cancelled configured SR transmissions that have been canceled over a predefined period, wherein the transmitting is conducted in response to the total number of cancelled configured SR transmissions exceeds a predetermined threshold; and refraining, by the UE, from transmission of the triggered SR in response to the total number of cancelled configured SR transmissions is less than the predetermined threshold.
 16. The method of claim 2, further including: comparing, by the UE, a transmission priority associated with a SR to a predetermined priority threshold, wherein the transmitting is conducted in response to the transmission priority exceeding the predetermined priority threshold; and refraining, by the UE, from transmission of the triggered SR in response to the transmission priority falling below the predetermined priority threshold.
 17. The method of claim 16, further including: receiving, by the UE, the predetermined priority threshold via one of: a radio resource control (RRC) configuration message or the bit field.
 18. The method of claim 2, wherein the transmitting includes: transmitting the triggered SR without other channel state information (CSI) and acknowledgement signals multiplexed therewith.
 19. The method of claim 1, further including: determining, by the UE, availability of transmission of the triggered SR on the transmission resource, wherein the transmitting occurs in response to a determination of transmission availability; and refraining, by the UE, from transmission of the triggered SR in response to a determination of transmission unavailability.
 20. The method of claim 19, further including: determining, by the UE, no successful SR transmissions over a predefined window of time; and performing, by the UE, a random access request procedure for an uplink transmission grant, in response to the determining the no successful SR transmissions.
 21. The method of claim 20, wherein the predefined window of time is one of: precoded into the UE; or received by the UE via control signaling from the serving base station.
 22. An apparatus configured for wireless communication, the apparatus comprising: at least one processor; and a memory coupled to the at least one processor, wherein the at least one processor is configured: to receive, by a user equipment (UE), a configuration message from a serving base station, wherein the configuration message configures a transmission resource for triggered scheduling request (SR) transmission; to monitor, by the UE, for a trigger signal triggering transmission of a triggered SR; and to transmit, by the UE, the triggered SR using the transmission resource in response to detecting the trigger signal.
 23. The apparatus of claim 22, further including configuration of the at least one processor: to receive, at the UE, a triggered SR configuration message that identifies a bit field within a control signal of the serving base station for the monitoring for the trigger signal.
 24. The apparatus of claim 23, further including configuration of the at least one processor: to receive, by the UE, a window length parameter, wherein the window length parameter is received in one of: the triggered SR configuration message or the bit field for the trigger signal; and to determine, by the UE, cancellation of one or more configured SR opportunities within a window length determined by the window length parameter, wherein the configuration of the at least one processor transmit the triggered SR is further in response to determination of the cancellation of the one or more configured SR opportunities within the window length.
 25. The apparatus of claim 23, wherein the transmission resource includes one of: a fixed resource for the triggered SR transmission; or a selected resource from a pool of transmission resources.
 26. The apparatus of claim 23, further including configuration of the at least one processor: to generate, by the UE, a pseudo-random variable known to the UE and the serving base station; to compare, by the UE, the pseudo-random variable to a preconfigured threshold, wherein the configuration of the at least one processor to transmit is executed in response to the pseudo-random variable falling within the preconfigured threshold; and to refrain, by the UE, from transmission of the triggered SR in response to the pseudo-random variable exceeding the preconfigured threshold.
 27. The apparatus of claim 23, further including configuration of the at least one processor: to determine, by the UE, a total number of cancelled configured SR transmissions that have been canceled over a predefined period, wherein the configuration of the at least one processor transmit is conducted in response to the total number of cancelled configured SR transmissions exceeds a predetermined threshold; and to refrain, by the UE, from transmission of the triggered SR in response to the total number of cancelled configured SR transmissions is less than the predetermined threshold.
 28. The apparatus of claim 23, further including configuration of the at least one processor: to compare, by the UE, a transmission priority associated with a SR to a predetermined priority threshold, wherein the configuration of the at least one processor to transmit is conducted in response to the transmission priority exceeding the predetermined priority threshold; and to refrain, by the UE, from transmission of the triggered SR in response to the transmission priority falling below the predetermined priority threshold.
 29. The apparatus of claim 23, wherein the configuration of the at least one processor to transmit includes configuration of the at least one processor to transmit the triggered SR without other channel state information (CSI) and acknowledgement signals multiplexed therewith.
 30. The apparatus of claim 22, further including configuration of the at least one processor: to determine, by the UE, availability of transmission of the triggered SR on the transmission resource, wherein the configuration of the at least one processor to transmit occurs in response to a determination of transmission availability; and to refrain, by the UE, from transmission of the triggered SR in response to a determination of transmission unavailability. 